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85 Cards in this Set
- Front
- Back
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net diffusion depends on
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concentration gradient, area of membrane, thickness of membrane, diffusion coefficient, partition coefficient
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partition coefficient
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concentration in olive oil / concentration in water
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diffusion coefficient depends on
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diameter of solute particle, viscosity of solution
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thickness of cell membrane affects diffusion how
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thicker the membrane, slower the diffusion
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what is flux?
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net diffusion of solute
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permeability equation
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p = (partition coefficient)(diffusion coefficient)/ thickness of membrane
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flux =
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(permeability) (area) (concentration gradient)
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osmosis
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flow of water across a semipermeable membrane because of differences in solute concentration
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osmolarity
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concentration of osmotically active particles in solution = (number of particles)(concentration)
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osmotic pressure =
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(number of particles)(concentration)(reflection coefficient)(gas constant)(absolute temperature)
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reflection coefficient
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1 = impermeable to solute, 0 = totally permeable to solute
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flow of water direction based on tonicity
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flows from hypotonic to hypertonic
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equilibrium potential
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diffusion potential that exactly balances the tendency for diffusion down concentration gradient
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nerst equation
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-2.3RT/zF (log (concentration inside)/(concentration outside)
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inward current
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flow of positive current into a cell, negative current
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outward current
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flow of positive charge out of cell, positive current
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tetrodotoxin
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blocks Na channels
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TEA
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blocks K channels
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why can no action potential happen during absolute refractory period
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inactivation gates of Na closed
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time constant
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how quickly a cell membrane depolarizes in response to inward current and how quickly it repolarizes in response to outward current
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time constant =
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(membrane resistance)(membrane capacitance)
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length constant
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how far a depolarizing current will spread along a nerve
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length constant =
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square root: (membrane resistance/internal resistance)
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internal resistance
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inversely related to the ease of current flow in the cytoplasm and inversely related to area of the nerve
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current will travel the farthest when...
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diameter is great, membrane resistance is high, internal resistance is low
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two ways to increase conduction velocity
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increase nerve diameter and myelinate (increases membrane resistance and decreases membrane capacitance)
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current of ions=
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= g (Emembrane - Eion)
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nicotinic receptors allow...
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both Na and K
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curare
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competes with Ach for receptor site (only stops action potential if concentration is high enough)
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2 factors controlling [Ach]
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amount released and rate at which it is removed
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2 ways to remove Ach
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diffusion and AChE
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reversal potential for EPP
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0 mV
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block AChE
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greater magnitude and duration EPPs
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when/where must calcium be in order for ACh to be released?
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in presynaptic terminal before release of ACh (depolarization in terminal --> allow Ca in)
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MEPP corresponds to
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1 vesicle containing ACh
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EPP=
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fusion of approximately 100 vesicles
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Increase the voltage strength of a stimulus...
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increase the force of twitch until a plateau
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motor unit
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motor neuron and all the fibers it innervates
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recruitment
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increase force by increasing number of muscle fibers recruited
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more excitable: small or large motor neurons
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small therefore recruited first
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tetanus
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single forceful contraction if great enough stimulation
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lowest frequency that shows summation =
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1/(duration of twitch)
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increase force by...
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increasing frequency of stimulation and increasing recruitment
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passive force
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stretched without activation (property of being elastic)
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isotonic contraction
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constant force after increasing force to reach afterload
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eccentric contraction
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lengthening the muscle, much more powerful than concentric
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the greater the cross sectional area of a muscle...
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the greater the force
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strap muscles
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high velocity, low force
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pinnate muscles
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low velocity, high force
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in spaces between myofibrils
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SR and glycogen
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titin
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spreads from Z-disc to M-line, helps myosin form
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alpha-actinin
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joins actin to Z-disc
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bindings of troponin
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C to calcium, T to tropomyosin, I inhibits interactions between thick and thin elements
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interaction of ATP, myosin and actin
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myosin binds ATP --> hydrolyzes it to ADP +Pi --> high affinity for actin --> binds --> dissociates from ADP + Pi --> power stroke --> rebind ATP --> lose affinity for actin
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muscle speed depends on
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rate of cross bridge turn over
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ANS made up of...
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sympathetic and parasympathetic
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tonic activity
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baseline activity, both sympathetic and parasympathetic
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how many neurons in somatic pathway?
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1
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how many neurons in autonomic pathway?
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2
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preganglionic neuron characteristics
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myelinated, fine, cell body in brainstem nucleus or lateral gray of spinal cord
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postganglionic neuron characteristics
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unmyelinated, cell body in ganglion
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location of sympathetic preganglionics
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intermediolateral column of thoraco-lumbar region (T1-L3)
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location of parasympathetic preganglionics
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cranial and sacral region
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path of preganglionic sympathetic
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enter ventral root --> white rami communicans --> sympathetic chain, up or down
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path of the postganglionic sympathetic
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gray rami communicans --> corresponding spinal nerve --> target organ
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three places where preganglionic sympathetic nerves synapse that are not in the sympathetic chain
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prevertebral or collateral: celiac ganglion, SM ganglion, IM ganglion
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chromaffin cells
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make up adrenal medulla, make endocrine products
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adrenal medulla innervation
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preganglionic sympathetics pass through sympathetic ganglion, celiac ganglion and synapse directly on chromaffin cells
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divergence
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one preganglionic nerve may innervate many postganglionic nerves
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convergence
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many preganglionic nerves may innervate a single postganglionic nerve
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parasympathetic nerve paths
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preganglionics from out of cranial or sacral and synapse with postganglionic right on target organ
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where are calcium spikes in relation to AP and muscle force
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in between
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where are triads
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at junction of A band and I band
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depolarization --> Ca release
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depolarize t-tubule --> DHPR opens at depolarization --> triggers RyR to open --> Ca comes out of SR --> Ca binds to TnC --> SERCA takes it back in and calsequestrin binds it
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after Ca binds to TnC...
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troponin complex changes shape --> TnT exposes binding site on actin --> myosin and actin bind
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series elastic component
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explains the delay in force transmitted to outside of the muscle and the delay in the fall of a force after Ca dissociates
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high frequency of stimulation effect on RyR
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stays open longer, Ca comes out more --> summation of transients
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which sympathetic targets have no parasympathetic innervation?
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hair follicles, sweat glands, smooth muscle of blood vessels
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ACh released by...
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parasympathetic and sympathetic preganglions AND parasympathetic postganglions AND sympathetic postganglions for sweat glands
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NE released by...
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sympathetic postganglionic (except sweat glands)
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when is peptide released, what does it do
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released during high frequency of stimulation, enhances effects of ACh and NE (neuropeptide Y)
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how is ACh cleared out?
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AChE
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what else is in vesicles with NE?
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ATP, dopamine beta hydroxylase
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how is NE cleared out?
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Na dependent transporters in membrane of postganglionic nerve (repackaged or metabolized)
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